Tuneable Singlet Exciton Fission and Triplet–Triplet Annihilation in an Orthogonal Pentacene Dimer. (4th August 2015)

• Record Type: Journal Article
• Authors: Lukman, Steven; Musser, Andrew J.; Chen, Kai; Athanasopoulos, Stavros; Yong, Chaw K.; Zeng, Zebing; Ye, Qun; Chi, Chunyan; Hodgkiss, Justin M.; Wu, Jishan; Friend, Richard H.; Greenham, Neil C.
• Is Part Of: Advanced functional materials. Volume 25:Number 34(2015)
• Page Start: 5452
• Page End: 5461
• Publication Date: 2015-08-04
• Subjects: dimers -- pentacenes -- singlet fission -- triplet–triplet annihilation -- vibrational relaxation; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201501537
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract : Fast and highly efficient intramolecular singlet exciton fission in a pentacene dimer, consisting of two covalently attached, nearly orthogonal pentacene units is reported. Fission to triplet excitons from this ground state geometry occurs within 1 ps in isolated molecules in solution and dispersed solid matrices. The process exhibits a sensitivity to environmental polarity and competes with geometric relaxation in the singlet state, while subsequent triplet decay is strongly dependent on conformational freedom. The near orthogonal arrangement of the pentacene units is unlike any structure currently proposed for efficient singlet exciton fission and may lead to new molecular design rules. Abstract : An orthogonal covalently bonded pentacene dimer (DP‐Mes) shows nearly quantitative singlet exciton fission on a sub‐picosecond timescale that is within the nuclear relxation time scale. By applying geometrical constraints, the fate of triplet–triplet annihilation is altered. These properties closely depend on molecular geometry and suggest a role for nuclear relaxation in controlling singlet exciton fission and triplet–triplet annihilation.